1. Field of the Invention
The present invention relates to a control system for an electric motor car.
2. Description of Related Art
An electric motor car has a regenerative brake that regenerates electric power during braking. The regenerated power is supplied for consumption to a power source unit of the same electric motor car or to another electric motor car through an overhead line. Power consumption by the power source unit of the same electric motor car is not always large, the power supplied to the other electric motor car is not always entirely consumed, or there is no other electric motor car. In these cases, power regeneration must be decreased by increasing mechanical frictional braking power and by wasting energy. When there are no other electric motor cars to consume regenerated power, the resistance of a brake chopper system may be used to convert the power into heat.
In this way, the regenerative brake system is not effectively used when energy demand is low due to the conditions of other electric motor cars or railroad tracks. If energy demand is low, the regenerative brake system must reduce regenerative power or convert regenerative power into heat. To effectively use regenerated energy, a related art disclosed in Japanese Unexamined Patent Application Publication No. 2003-199204 stores regenerated energy in an electric double layer capacitor.